Callovian

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The Callovian is a stage on the geologic time scale occurring 164.7 ± 4.0 Ma to 161.2 ± 4.0 Ma (million years ago). It is the last stage of the Middle Jurassic.

The stage takes its name from an old spelling of Kellaways Bridge, 3 km north-east of Chippenham in Wiltshire in England.

Contents 1 Geography 2 Vertebrate Fauna 2.1 Crocodylomorphs 2.2 Ornithischians 2.3 Plesiosaurs 2.4 Sauropods 2.5 Stegosauria 2.6 Theropods 3 Invertebrate Fauna 3.1 Ammonitida 3.2 Belemnites 3.3 Nautiloids 3.4 Neocoleoids 4 References

[edit] Geography

During the Callovian, Europe was an Archipelago of a dozen or so large islands. Between them were extensive areas of continental shelf. Consequently, there are Callovian deposits in Russia and from Belarus, through Poland and Germany, into France and eastern Spain and much of England. Around the former island coasts are frequently, land-derived sediments. These are to be found, for example, in western Scotland. (Elmi & Babin fig.55.)

[edit] Vertebrate Fauna

[edit] Crocodylomorphs

Crocodylomorphs of the Callovian
Taxa	Presence	Location	Description	Images
Junggarsuchus			The sphenosuchian Junggarsuchus was a small, ~1 meter long, Chinese predator.	A life restoration of a Metriorhynchus species.
Metriorhynchus			An opportunistic carnivore that fed on fish, belemnites and other marine animals and possible carrion. Metriorhynchus grew to an average adult length of 3 meters (9.6 ft), although some individuals may have reached lengths rivaling those of large nile crocodiles.
Steneosaurus

[edit] Ornithischians

Ornithischia of the Callovian
Taxa	Presence	Location	Description	Images
Agilisaurus		Dashanpu Formation, Sichuan, China	A four-foot long bipedal herbivore that was built for speed. It was discovered in one of China's many Callovian deposits.	Agilisaurus
Callovosaurus		England	A primitive camptosaurid iguanodont, estimated to have been 3.5 meters long
Ferganocephale		Kyrgyzstan	Possibly an early pachycephalosaurid
Hexinlusaurus Hexinlusaurus multidens	Bathonian to Callovian	Lower Shaximiao Formation, Sichuan, China	A small ornithischian dinosaur distinguished from all other basal ornithischians by a single autapomorphy, the presence of a marked concavity that extends over the lateral surface of the postorbital.

[edit] Plesiosaurs

Plesiosaurs of the Callovian
Taxa	Presence	Location	Description	Images
Liopleurodon				Liopleurodon was a large pliosaur from the Callovian stage. Peloneustes Pliosaurus Simolestes vorax
Pachycostasaurus
Peloneustes
Pliosaurus
Simolestes

[edit] Sauropods

Sauropods of the Callovian
Taxa	Presence	Location	Description	Images
Abrosaurus			Abrosaurus was a small (30 foot adult length) sauropod from China with an unusual skull.	Abrosaurus.
Atlasaurus
Ferganasaurus Ferganasaurus verzilini			:A Kyrgistani sauropod genus that resembled Rhoetosaurus.
Patagosaurus

[edit] Stegosauria

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Stegosaurs of the Callovian
Taxa	Presence	Location	Description	Images
Huayangosaurus	Bathonian to Callovian	Lower Shaximiao Formation, Sichuan, China	A 4.5 meters in length quadrupedal herbivore with a small skull and a spiked tail. Bore the distinctive double row of plates, rising vertically along its arched back, of all the stegosaurians and two pairs of long spikes extending horizontally near the end of its tail	Huayangosaurus
Lexovisaurus		Lisieux, France; Northern England	Traditionally, Lexovisaurus was depicted as having either large spines over the hips or shoulders, with a selection of flat plates and round pointed spines that ran along the back and tail. It was probably about 5 m long.
Loricatosaurus		France; England	Known from remains previously assigned to Lexovisaurus.

[edit] Theropods

theropods of the Callovian
Taxa	Presence	Location	Description	Images
Eustreptospondylus			A moderately large (17-23 feet long) predatory dinosaur that was closely related to Megalosaurus.	Eustreptospondylus.
Gasosaurus Gasosaurus constructus			An 11-13 foot predator from China whose discovery was assisted by the petroleum industry.
Pedopenna
"Szechuanoraptor"			A Chinese theropod that has yet to be formally described.

[edit] Invertebrate Fauna

[edit] Ammonitida

Members of the order ammonitda are known as Ammonitic ammonites. They are distinguished primarily by their suture lines. In ammonitic suture patterns, the lobes and saddles are much subdivided (fluted) and subdivisions are usually rounded instead of saw-toothed. Ammonoids of this type are the most important species from a biostratigraphical point of view. This suture type is characteristic of Jurassic and Cretaceous ammonoids but extends back all the way to the Permian.

Ammonites of the Callovian
Taxa	Presence	Location	Description	Images
Cadomites				Life restorations of two different ammonite genera.
Oecoptychius
Oecotraustes
Oxycerites

[edit] Belemnites

Belemnites of the Callovian
Taxa	Presence	Location	Description	Images
Produvalia				Small belemnite fossils

[edit] Nautiloids

Nautiloids of the Callovian
Taxa	Presence	Location	Description	Images
Somalinautilus				An illustration of a variety of fossil nautiloids.

[edit] Neocoleoids

Neocoleoids of the Callovian
Taxa	Presence	Location	Description	Images
†Proteroctopus Proteroctopus ribeti				Pyritized fossil of Vampyronassa rhodanica from Voulte-sur-Rhône, France.
†Rhomboteuthis Rhomboteuthis lehmani			A squid species discovered in France.
†Vampyronassa Vampyronassa rhodanica

[edit] References

Serge Elmi and Claude Babin, Histoire de la Terre, 4th Edition Dunod, Paris (2002) ISBN 2 10 006631 5 (French language)

Jurassic period
Lower/Early Jurassic	Middle Jurassic	Upper/Late Jurassic
Hettangian | Sinemurian Pliensbachian | Toarcian	Aalenian | Bajocian Bathonian | Callovian	Oxfordian | Kimmeridgian Tithonian